Présentation d'une méthode d'étude de la stabilité linéaire d'écoulements instationnairesPresentation of a method for linear stability analysis of unsteady flow

We propose a linear stability analysis of unsteady viscous flow. We apply this method to an oscillatory pipe flow with an axisymetric 2D perturbation which has received considerable attention. The numerical results are relevant. To cite this article: M. Siouffi et al., C. R. Mecanique 330 (2002) 641–645.     

Quo Vadis Advanced Prostate Cancer Therapy? Novel Treatment Perspectives and Possible Future Directions

Prostate cancer is a very common disease, which is, unfortunately, often the cause of many male deaths. This is underlined by the fact that the early stages of prostate cancer are often asymptomatic. Therefore, the disease is usually detected and diagnosed at late advanced or even metastasized stages, which are already difficult to treat. Hence, it is important to pursue research and development not only in terms of novel diagnostic methods but also of therapeutic ones, as well as to increase the effectiveness of the treatment by combinational medicinal approach. Therefore, in this review article, we focus on recent approaches and novel potential tools for the treatment of advanced prostate cancer; these include not only androgen deprivation therapy, antiandrogen therapy, photodynamic therapy, photothermal therapy, immunotherapy, multimodal therapy, but also poly(ADP-ribose) polymerase, Akt and cyclin-dependent kinase inhibitors.     

Surface modification of oxidized cellulose haemostat by argon plasma treatment

In this paper we focused on cold plasma treatment of oxidized cellulose haemostat. Oxidized cellulose was modified in inert argon plasma. The changes of surface composition were examined by XPS and FTIR. Surface morphology of fibres was studied by SEM. Gravimetry was used to study ablation and water absorption. Antibacterial effect of pristine and plasma treated samples was examined by growth of Escherichia coli and Staphylococcus epidermidis. Behaviour of pristine and plasma treated samples in water, physiological saline solution and phosphate buffered saline was observed by changes in the pH of their solutions. Modification of oxidized cellulose by inert argon plasma caused significant changes in the chemical composition of its surface layers as well as changes in morphology of those layers while maintaining or improving the antibacterial properties. We found out that modification by inert argon plasma improves the properties necessary for haemostatic function of oxidized cellulose.     

Crocoite PbCrO4 and mimetite Pb5(AsO4)3Cl: rare minerals in highly degraded mediaeval murals in Northern Bohemia

Mural paintings of exceptional quality, which can be discerned in spite of their extensive mechanical damage and colour fading, have been uncovered in the church of St. Gallus in Kuřívody, Northern Bohemia, dated to the second half of the 13th century. Materials research with particular use of portable X‐ray fluorescence, Raman micro‐spectroscopy and powder X‐ray micro‐diffraction revealed the presence of rare pigments. In Kuřívody, it is only a second identification of intentionally used yellow mineral crocoite (PbCrO₄) in European art. Its identification is facilitated by providing a very good Raman scattering, even when present in small amounts in fragmentarily preserved colour layers. Light yellow mimetite (Pb₅(AsO₄)₃Cl) was never before mentioned as intentionally used pigment in Europe. Its finding in Kuřívody, however, corresponds more likely with undesirable physical–chemical conditions causing its formation by alteration of orpiment (As₂S₃) and minium (Pb₃O₄). Obtained results highlight the importance of Raman spectroscopy for direct identification of mineral pigments in low concentrations, which may be crucial for interpreting cultural heritage objects in historical context. By materials, the almost forgotten paintings in Kuřívody can be seen as outstanding and rare example of ancient artistic tradition that has spread to Europe from Mediterranean in early Middle Ages. After all, mineral crocoite was already used by ancient Egyptians to paint sarcophagi and degraded orpiment decorates the walls of the Nefertari's tomb in Thebes. Copyright © 2014 John Wiley & Sons, Ltd.     

Micro-analytical evidence of origin and degradation of copper pigments found in Bohemian Gothic murals

Correct identification of pigments and all accompanying phases found in colour layers of historical paintings are relevant for searching their origin and pigment preparation pathways and for specification of their further degradation processes. We successfully applied the analytical route combining non-destructive in situ X-ray fluorescence analyses with subsequent laboratory investigation of micro-samples by optical microscopy, scanning electron microscopy/energy-dispersive spectroscopy and X-ray powder micro-diffraction (micro-XRD) to obtain efficiently all the data relevant for mineralogical interpretations of the copper pigments origin. Cu salts (carbonates, chlorides, sulphates, etc.) used as pigments exist in a range of polymorphs with similar or identical composition. The efficiency of the micro-XRD for direct identification of such crystal phases present in micro-samples of colour layers was demonstrated in the presented paper. A new, until now unpublished, type of copper pigment—cumengeite, Pb₂₁Cu₂₀Cl₄₂(OH)₄₀—used as a blue pigment on a sacral wall painting in the Czech Republic was found by means of micro-XRD. Furthermore, azurite, malachite, paratacamite, atacamite and posnjakite were identified in fragments of colour layers of selected Gothic wall paintings. We found Cu–Zn arsenates indicating the natural origin of azurite and malachite; artificial malachite was distinguishable according to its typical spherulitic crystals. The corrosion of blue azurite to green basic Cu chloride was clearly evidenced on some places exposed to the action of salts and moisture—in a good agreement with the results of laboratory experiments, which also show that oxalic acid accelerates the corrosion of Cu pigments.     

Evaluation of laboratory powder X-ray micro-diffraction for applications in the fields of cultural heritage and forensic science

The uniqueness and limited amounts of forensic samples and samples from objects of cultural heritage together with the complexity of their composition requires the application of a wide range of micro-analytical methods, which are non-destructive to the samples, because these must be preserved for potential late revision. Laboratory powder X-ray micro-diffraction (micro-XRD) is a very effective non-destructive technique for direct phase analysis of samples smaller than 1 mm containing crystal constituents. It compliments optical and electron microscopy with elemental micro-analysis, especially in cases of complicated mixtures containing phases with similar chemical composition. However, modification of X-ray diffraction to the micro-scale together with its application for very heterogeneous real samples leads to deviations from the standard procedure. Knowledge of both the limits and the phenomena which can arise during the analysis is crucial for the meaningful and proper application of the method. We evaluated basic limits of micro-XRD equipped with a mono-capillary with an exit diameter of 0.1 mm, for example the size of irradiated area, appropriate grain size, and detection limits allowing identification of given phases. We tested the reliability and accuracy of quantitative phase analysis based on micro-XRD data in comparison with conventional XRD (reflection and transmission), carrying out experiments with two-phase model mixtures simulating historic colour layers. Furthermore, we demonstrate the wide use of micro-XRD for investigation of various types of micro-samples (contact traces, powder traps, colour layers) and we show how to enhance data quality by proper choice of experiment geometry and conditions.     

Study of phase transformation temperatures of alloys based on Fe–C–Cr in high-temperature area

Three alloys based on Fe–C–Cr were studied. These alloys contained carbon in a range of 0.308–0.380 mass% and chromium 1.058–4.990 mass%. Temperatures of solidus (onward used as T_S), liquidus (onward used as T_L) and peritectic transformation (onward used as T_P) were studied in the high-temperature region. These temperatures were obtained using two thermal analysis methods: differential thermal analysis (onward used as DTA) and simple thermal analysis (onward used as TA). The Setaram Setsys 18_TM was used for experiments with employment of the DTA method. All measurements were taken in an inert atmosphere of pure argon at heating rate of 10 °C min^?1, and simple TA method was used for the experiments with the use of the Netzsch STA 449 F3 Jupiter. Measurements were taken in inert atmosphere of pure argon at a heating and cooling rate of 5 °C min^?1. Phase transformation temperatures were obtained by heating and cooling process and were approximated to “equilibrium conditions” (DTA method: zero heating rate and sample mass, standard, TA method: only standard) (?aludová et al. in J Therm Anal Calorim 112:465–471, 2013a. doi: https://doi.org/10.1007/s10973-012-2847-8; J Therm Anal Calorim 111:1203–1210, 2013b. doi: https://doi.org/10.1007/s10973-012-2346-y). The experimental data were compared and discussed with the calculation results using IDS (solidification analysis package) software (onward used as SW) Thermo-Calc and the TCFE8 (Thermo-Calc Fe-based alloys) database. The results of the two alloys were compared with those published for similar steels. The experimentally obtained transition temperatures were close to the calculated values. The solidus, liquidus and peritectic transformation temperatures were lowered with increasing carbon (range 0.308–0.380 mass%) and chromium content (range 1.058–4.990 mass%). The smallest difference between the experimental results and theoretical calculations was observed at the liquidus temperature for all alloys. Nonetheless, the difference measured for the solidus temperatures was much greater.